The invention relates to the class of machines used to promote aerobic and muscle building exercise. In particular, this machine, in its simplicity, offers a high degree of adjustability to size the device to the physiology of the individual and tailor the force characteristics to accommodate varying effort needs. Prior machines have used complex linkages or sliding based mechanisms in their attempts to achieve this objective. This machine is designed around an easily adjustable four bar linkage combined with an adjustable and configurable counterbalance force function. The tailoring of this counterbalance force increases or decreases the effort and thus moves between aerobic and muscle building effort. The counterbalance force more particularly is provided by robber extension springs. Additionally, it may be sized to the exercising individual by adjusting seat position and handle position through the adjustment of the control link length.
The invention described herein offers improvements over the prior art in its simple construction, variable counter force configureability, adjustable sizing, and collapsibility for compact storage.